1. If you have samples of n1=23 and n2=17, in performing the pooled-variance t test, how many degrees of freedom do you have?

You have____ degrees of freedom?

2. Assume that you have a sample of n1=7, , with the sample mean X1=43, , and a sample standard deviation of S1=4, and you have an independent sample of n2=13 from another population with a sample mean of X2=35 and the sample standard deviation S2=5.

Complete parts (a) through (d) below.

a. What is the value of the pooled-variance t test statistic for testing ? tSTAT H0 : 1 = 2

tSTAT = __________

(Round to two decimal places as needed.)

b. In finding the critical value, how many degrees of freedom are there?

_____________degrees of freedom

(Simplify your answer.)

c. Using a significance level of = 0.01, what is the critical value for a one-tail test of the hypothesis H0 : 1 against the alternative H1: 1 > 2 ?

The critical value is ___________.

(Round to two decimal places as needed.)

d. What is your statistical decision?

A. Do not reject H0 because the computed tSTAT test statistic is less than the upper-tail critical value.

B. Reject H0 because the computed tSTAT H test statistic is greater than the upper-tail critical value.

C. Reject H0 because the computed tSTAT H test statistic is less than the upper-tail critical value.

D. Do not reject H0 because the computed tSTAT test statistic is greater than the upper-tail critical value.

3. Assume that you have a sample of n1=8 , with the sample mean x1=42, , and a sample standard deviation of S1=4 , and you have an independent sample of n2=15, from another population with a sample mean of X2=34 and a sample standard deviation of S2=5 . What assumptions about the two populations are necessary in order to perform the pooled-variance t test for the hypothesis H0:u1=u2 against the alternative H1:u1 >u2 and make a statistical decision?

Choose the correct answer below.

A. It is necessary to assume that the populations from which you are sampling have equal population means and positive standard deviations.

B. It is necessary to assume that the populations from which you are sampling have independent normal distributions and equal variances.

C. It is necessary to assume that the populations from which you are sampling have negative tSTAT test statistics and unequal sample means.

D. It is necessary to assume that the populations from which you are sampling have unequal variances and equal sizes